This invention relates to a method for treating dry eye. In particular, solutions comprising a cationic cellulosic polymer have been found useful for alleviating the symptoms of dry eye.
Dry eye, also known generically as keratoconjunctivitis sicca and dyslacrima, is a common ophthalmological disorder affecting millions of people. A patient with dry eye may experience burning, a feeling of dryness and persistent irritation. In severe cases, dry eye can seriously impair a person""s vision and hence handicap the sufferer in activities such as driving. Certain diseases such as Sjogren""s disease manifest dry eye symptoms. Also, as people age, the lacrimal ducts in the eye may produce less moisture, resulting in eyes that become dry, inflamed, itchy and gritty.
Although it appears that dry eye may result from a variety of underlying, unrelated pathogenic causes, all presentations of the condition share a common effect, namely the breakdown of the pre-ocular tear film, which commonly results in dehydration of the exposed outer surface and hence the symptoms described above.
A number of approaches exist for the treatment of dry eye. One common approach has been to supplement the ocular tear film using artificial tears instilled throughout the day. Examples of the tear substitute approach include the use of buffered, isotonic saline solutions and aqueous solutions containing water-soluble polymers that render the solutions more viscous and thus less easily shed by the eye by the washing action of the tear fluid. See, for example, U.S. Pat. No. 5,209,927 to Gressel, et al.; U.S. Pat. No. 5,294,607 to Glonek, et al.; and U.S. Pat. No. 4,409,205 to Shively.
Although these approaches have met with some success in some cases, significant challenges in the treatment of dry eye nevertheless remain. Problems include the fact that the use of tear substitutes, while temporarily effective, generally require repeated application over the course of a patient""s waking hours, not uncommonly ten to twenty times over the course of a day. Such an approach is not only inconvenient and time consuming, but not very effective in preventing at least the initiation of dry-eye symptoms. Although increasing the viscosity of the dry-eye product may extend the product""s duration in the eye to a limited extent, still further increases in duration would be highly desirable.
U.S. Pat. No. 5,645,827 to Marlin, et al. discloses the use of compositions comprising a cationic polysaccharide in combination with an anionic therapeutic agent, for example, hyaluronic acid or its salt, which is a known demulcent for the treatment of dry eye. Marlin, et al. believe that the anionic therapeutic agent is electrostatically bonded to the cationic polysaccharide which in turn is substantive to the mucosal surface. Substantivity is characterized by an increase of the cationic polysaccharide on the mucosal surface and can be measured through the use of an ocular fluorometer. European Application 088770 Al to Marlin et al. discloses cationic cellulose polymers to deliver cationic therapeutic agents, especially for the treatment of glaucoma.
U.S. Pat. Nos. 4,436,730 and 5,401,327 to Ellis, et al. disclose the use of cationic cellulosic derivatives in contact-lens treating solutions, including the combination of a cationic cellulose polymer and an ethoxylated glucose such as glucam. In column 4, lines 42-57, the latter patent states that the combination of a cationic cellulose material with a PEO component such as glucam is particularly advantageous for the reason that the cationic component complexes with the PEO component and the complex more strongly absorbs on the lens surface. The cationic cellulose polymer and entangled PEO is believed to reach into the aqueous phase to provide cushioning and protein resistance.
German Application DE 3440352 teaches a treatment for dry eye that contains an acrylate-based dry eye gel, containing from 0.2 to 1.0 parts acrylate polymer such as Carbopol), 0.15 to 3 parts base (such as NaOH), and remainder water; and a dry eye solution containing 0.1 to 1 part by weight water-soluble cationic cellulose derivatives (such as various UCAREO(copyright) Polymer JR), 0.5 parts by weight of an isotonic agent and remainder water.
In view of the above, it would be desirable to provide an eye-drop solution that will better alleviate the symptoms of dry eye and that is safe, convenient and economical to use. In particular, it would be highly desirable to develop a product having significantly greater duration of efficacy, in order to significantly decrease the number of times that the product may need to be administered to the eye, over the course of a day, in order to effectively treat the symptoms of dry eye.
The present invention is directed to a method of treating dry eye employing a solution comprising an effective amount of a cationic cellulose for alleviating the symptoms of dry eye. Such solutions are effective in the absence of hyaluronic acid and other anionic therapeutic agents. The invention is also directed to a method of using the foregoing composition to treat the symptoms of dry eye. In one preferred embodiment, the method employs a solution having low ionic strength. In another preferred embodiment, the method employs a solution having relatively low concentrations of mono- or di-saccharides. In a particularly preferred embodiment, the solution of the invention is essentially free of chloride ions and essentially free of mono- or di-saccharides.